Most conventional pick-up truck box extenders are installed inside of a truck box and it occupies certain inside volume thereof. Therefore, most of pick-up truck owners stretch the extender unnecessarily though the inside volume of the truck box is large enough. To lead a bulky cargo, the extender must be detached from the truck box first. Load the cargo into the box and then attach the extender again. The extender becomes another load. However, it is still unstable to load a tall cargo due to the fixed length of the extender. Using the conventional extender as a divider is limited because size of each cargo is different. In addition to this, if a toolbox is already mounted in the truck box, it is very hard to carry additional cargo such as a long size ladder or leisure items like bicycles, motorcycles, etc. It is a purpose of the current application to provide a pick-up truck box extender that occupies minimum space of the truck box and enables to carry additional cargos such as long ladder, bicycles and motorcycles without detaching the extender from the truck cargo box. Another purpose of the current application is to provide an adjustable truck box extender that has racks for legs of a long ladder and wheels of bicycles and motorcycles to load them on the truck more securely and safely